Near field communication (NFC) is defined as the communication standard for the close proximity wireless communication technology. As the communication mode used between apparatuses, NFC defines the following three modes: the card emulation function that allows the user to use an apparatus as an integrated circuit (IC) card, the reader/writer function that writes and reads data to and from an IC card, and the terminal-to-terminal communication function that carries out two-way communication between NFC-compatible apparatuses.
NFC also defines a capability used by an apparatus on the connection requesting side (link activating side) to obtain information about a mode and a protocol supported by an apparatus on the other end (link activated side). Based on the obtained mode and the protocol supported by the apparatus on the other end, NFC defines a capability used by the apparatus on the connection requesting side to select and set a mode and a protocol that the apparatus is to use (ETSI TS 102 622 “Smart cards; UICC—Contactless Front-end (CFL) Interface; host controller Interface” Technical Specification).
NFC defines two operation modes: one is the mode (active mode) in which the NFC interface operation is performed with the power supplied from an apparatus itself and the other is the mode (passive mode) in which the NFC interface operation is performed with the power (induced electromotive force) supplied from another apparatus. Usually, the NFC communication via the card emulation function operates in the passive mode.
A technology is discussed in which a universal integrated circuit card (UICC), a smart card used in a mobile phone, is activated upon detection of proximity to another device (proximity determination by the detection of induced electromotive force). Another technology is discussed in which a contactless IC card file system service, included in a UICC, is activated upon detection of proximity to another device.
A still another technology is discussed in which the NFC interface operation of an apparatus is changed to the active mode (the mode in which the NFC interface operation is performed by the power supplied from the apparatus itself) upon detection of the absence of radio waves in the NFC interface (proximity determination by the detection of the absence of induced electromotive force) (Japanese Patent Application Laid-Open No. 2010-273373)
A mobile apparatus, in which NFC is installed, usually includes a host processor that controls the entire apparatus and a large scale integration (LSI) that controls the NFC interface. To perform the reader/writer emulation function and the terminal-to-terminal communication function in this configuration, the apparatus needs to start the host processor, which controls the entire apparatus, to start a corresponding application. On the other hand, the apparatus can perform the card emulation function, capable of operating in the passive mode, to communicate with an apparatus at the other end without having to start the host processor. In addition, the mobile phone, which performs communication via NFC as a link-activated apparatus, needs to have its host processor placed in the started state to notify the link activating side that the reader/writer emulation function and the terminal-to-terminal communication function are supported on the mobile apparatus.
However, from a power consumption point of view, it is undesirable to start power-consuming hardware, such as the host processor, each time communication is performed via NFC (proximity is detected) to support the modes. For example, to communicate with an apparatus at the other end to perform the card emulation function only, the host processor does not need to be started each time communication is performed via NFC. Therefore, from a power consumption point of view, it is desirable that power-consuming hardware, such as the host processor, be started only when needed during NFC communication.